Study of enrichment of vermiculite ores of the «Tebinbulak» deposit of the Republic of Uzbekistan Avaz Aripov, Fozil Akhtamov, Quvonchbek Bektamishov, Aslonbek Ikromov, Farxod Erkinov

Study of enrichment of vermiculite ores of the «Tebinbulak» deposit of the Republic of Uzbekistan
Avaz Aripov, Fozil Akhtamov, Quvonchbek Bektamishov, Aslonbek Ikromov, Farxod Erkinov
Navoi State University of Mines and Technologies, Navoiy, Uzbekistan
Abstract. The mineralogical and technological properties of vermiculite raw materials are analyzed in the article, the main properties of natural vermiculite are studied. As a result of the tests, a technological scheme for dry beneficiation of vermiculite ores was developed. The output of vermiculite concentrate by fractions is 10.57%, its amount in enrichment is 85%, the separation of vermiculite in enrichment is 95.95%.
Keywords: Ore, minerals, vermiculite, air separator, grinding, settling, drying, thermal insulation, temperature, beneficiation, fractions, technological scheme.
1. Introduction cc
The production of vermiculite and materials based on it has just begun to develop in the Republic of Uzbekistan. high porosity, low density and low thermal conductivity, as well as high fire resistance and stability of the mineral content made it widely used among other heat-insulating materials. Dry building mixes are made from it, fire-resistant boards and paints are produced, it is widely used in insulation of heating devices and soundproofing of rooms, steel casting [1].
Currently, 500-600 thousand tons of vermiculite is produced annually worldwide, about 80% of which is mined in the USA and the Republic of South Africa, and the rest in Brazil, Argentina, China, India, Egypt, Kenya and Russia [2]. more than one hundred types of vermiculite products are produced in economically developed countries [3]. In most countries, the use of vermiculite is still limited due to the fact that the building materials production industry is not equipped with modern energy and resource-saving technologies. Expanded vermiculite is widely used as an effective thermal and sound insulation material, porous filler for lightweight concrete and plastering admixtures, and other purposes [4].
Vermiculite is widely used in steel casting, water filtration, as an adsorbent of smoke and toxic gases, as an anti-radiation material, in wastewater treatment, in oil spill recovery, and in reducing soil nitrate pollution [2]. Agro vermiculite is widely used in horticulture and floriculture in developed countries with high agricultural culture [5].
In the steel and iron-based alloy casting industry, the melting of any metal is always associated with high temperatures, so a reliable refractory material is required to ensure the operability of the technological processes and to protect the equipment. Vermiculite can withstand temperatures above 1300⁰C and provides low thermal conductivity. Excellent adsorption properties of vermiculite are used in cases of disruption of technological processes in the production of chemical reagents, alkalis and acids.
When it comes to the use of vermiculite in the energy industry, it is primarily used in atomic energy due to its ability to reflect gamma radiation and absorb the destructive radiation of radioactive isotopes including strontium, cesium, cobalt, and others. It is also used to create fire-resistant protection for high-voltage electric cables and distribution boxes, to organize fire barriers in energy complex facilities. The process of applying vermiculite to many branches of the engineering industry began: in the automotive industry, it is one of the main components in the production of brake pads and other friction products, effectively reducing the temperature that occurs during high-speed friction allows (has high physical and mechanical properties), as a result, the service life increases [2]. In the aircraft industry, based on the fire-resistant properties of vermiculite, special coatings have been created for runways that have the ability to quickly extinguish (reduce) the temperature during braking. In shipbuilding, vermiculite is included in the coatings used for the underwater part of ships. This prevents the growth of molluscs on the ship's hull. Fire-resistant parts and thermal insulation in ships and cars are also produced on the basis of vermiculite [2].
Adsorption properties of vermiculite open a wide way for its use in the food industry. The natural origin of this material makes it possible to use it for filtering water and all kinds of suspensions (sugar syrup, starch and molasses-based products, vegetable oils, alcohol products and beer, fruit and vegetable juices). In addition, vermiculite serves as insulation in food storage in industrial refrigerators. Expanded vermiculite is used for thermal insulation of walls, floors, foundations, and sound insulation of buildings.
The purpose of beneficiating vermiculite is to separate it from loose non-expandable rock and weakly expandable micas. This process is the most complex and expensive in the production of expanding vermiculite. The next stages of raw material processing - crushing and burning are performed with less labor and costs. Their presence in the final product has almost no effect on the quality of expanding vermiculite, because currently there are methods of waste and enrichment processing that allow the complete separation of biotite and phlogopite particles directly as a result of the incineration process [2].
In Uzbekistan, the production of vermiculite and materials based on it began to develop in the last five years. Instead of the technology of enrichment based on combustion, which is widely used in world practice, in the conditions of today's constant increase in the price of oil and gas products and their shortage, as well as increasing environmental requirements, increasing requirements for its quality, saving energy and resourcesand in the conditions of industrial safety, there was a need to develop production in new directions, vermiculite enrichments and conglomerate (from the Latin conglomeratus - crowded, compressed, a mixture of various dissimilar things, irregular addition, assorted) sets the task of creating a new concept of processing technological systems [1]. In beneficiation of vermiculite ores, sedimentation and dry magnetic separation processes are used. At the Kovdor beneficiation plant (Russia), ore is successively beneficiated by grinding, sorting, and separated into finished product (vermiculite), waste and intermediate products. Developed a technology for extracting expanding vermiculite from under-enriched vermiculite ore by incineration in a specialized electric furnace and simultaneous separation of inert material [2].
The highest quality vermiculite enrichment is obtained from the Kovdor vermiculite mine, which is a product of hydration. Technologies for beneficiation of Potanin, Altintas, Karatas, Barchin, Sholak-Kayraktan mines (Russia) have also been developed. The ores of a number of mines were tested in pilot-industrial conditions and included in the state reserve based on the proposed solutions for their processing [2].
Vermiculite can be burned in different furnaces (gaseous or liquid-fueled tower, rotary tube, etc.). The most effective way to burn vermiculite is in a fluidized bed furnace. Tower furnaces overcome this condition, providing intensive heating of vermiculite grains and their short stay in the high temperature zone. The impossibility of separating waste rocks is an important drawback of the incineration process [3].
Based on the analysis of available works, it has been established that vermiculite ores are one of the most difficult problems to solve, since it is difficult to separate them from non-intumescent loose rocks and slightly intumescent micas during enrichment and production of various products. At the same time, the problems of improving the quality of vermiculite ores, improving technological processes aimed at the widespread use of these products in order to obtain refractory materials from them have not been sufficiently studied.